JP5099319B2 - Hologram imaging optical system - Google Patents

Description

  The present invention relates to a holographic imaging optical system, and more particularly to a holographic imaging optical system that corrects aberrations caused by closely attaching a prism to the incident side of a hologram photosensitive material when an image hologram is recorded.

  Depending on the imaging conditions of the hologram to be manufactured, the incident angle of light in the hologram photosensitive material may be greater than or equal to the critical angle of the photosensitive material, and the light flux may not be incident from the air. In such a case, a prism made of a parallel plate having an appropriate slope is brought into close contact with the hologram photosensitive material, and reference light is incident on the photosensitive material at an incident angle greater than the critical angle from the slope, and object light is incident from the upper surface of the prism. There is a photographing method in which a hologram is photographed by two-beam interferometry with incidence.

  FIG. 3 shows an optical arrangement in that case. The hologram photosensitive material 10 is attached to the back side surface 22 of the prism 20 having the front side surface 23, the back side surface 22 and the slope 21 which are parallel to each other directly or via a refractive index matching liquid, and the reference light 12 passes through the slope 21 of the prism 20. Is incident on the hologram photosensitive material 10 at an incident angle greater than the critical angle, and the object light 11 is incident through the front side surface 23 of the prism 20, and the object light 11 and the reference light 12 incident on the hologram photosensitive material 10 are mutually transmitted. A transmission hologram is recorded by interference.

  When a hologram is recorded as an image hologram in such an arrangement, the hologram photosensitive material 10 is generally tilted with respect to the optical path of the object light 11 (the normal of the hologram photosensitive material 10 has an angle with respect to the optical axis of the object light optical path). Therefore, the pattern plate 5 projected onto the surface by the projection optical system 7 is also tilted in the opposite direction corresponding to the tilt.

The object light 11 and the reference light 12 are generated as follows, for example. That is, the laser beam generated by the laser 1 is divided into two by the half mirror 2, and the laser beam reflected by the half mirror 2 is converted into a predetermined beam diameter by the beam expander 4 through the mirror 3 and recorded as a hologram. Illuminate 5. The light transmitted and scattered by the pattern plate 5 enters the front side surface 23 of the prism 20 as object light 11 through the projection optical system 7 and enters the hologram photosensitive material 10 at a predetermined angle. On the other hand, the laser beam that has passed through the half mirror 2 is made to have a predetermined beam diameter by the beam expander 9 through the mirror 8, enters the inclined surface 21 of the prism 20 as reference light 12, and enters the hologram photosensitive material 10 at a predetermined angle greater than a critical angle. Incident at an incident angle.
JP 2005-115225 A

  However, in the optical arrangement as shown in FIG. 3, the object beam 11 is incident obliquely on the front side surface 23 of the prism 20, so that the image on the hologram photosensitive material 10 of the pattern plate 5 has an aberration such as astigmatism. This causes a problem that the resolution is lowered.

  Further, since the pattern plate 5 is also tilted, when the parallel plate 6 is arranged on the exit side, astigmatism is caused by the parallel plate 6 and the resolution is further lowered.

  The present invention has been made in view of the above-described problems of the prior art, and its object is to adhere a prism to the incident side of a hologram photosensitive material tilted with respect to object light to be recorded as an image hologram. It is an object of the present invention to provide a hologram photographing optical system arranged to correct the generated aberration.

In the hologram imaging optical system of the present invention that achieves the above object, a transparent medium is disposed in close contact with the hologram photosensitive material in the optical path of the object light, and the object light from the pattern plate disposed in the optical path of the object light is In a holographic imaging optical system that shoots an image hologram by being incident on a transparent medium,
Projection optics for projecting the pattern plate onto the hologram photosensitive material through the transparent medium while arranging the object light from the pattern plate to be substantially perpendicular to the surface on the object light incident side of the transparent medium A double-sided telecentric optical system is used as the system.

  In this case, another transparent medium is arranged on the emission side of the pattern plate, and is arranged so that the object light from the pattern plate is emitted substantially perpendicularly from the surface of the other transparent medium on the object light emission side. It is desirable.

  Further, as the double-sided telecentric optical system, an optical system in which two groups of positive lenses are disposed concentrically and coaxially and a stop is disposed on the common focal plane can be used.

  Further, the reference light may be incident from another side surface of the transparent medium.

  Alternatively, the reference light may be incident from the opposite side of the hologram photosensitive material from the transparent medium side.

  In the present invention, it is possible to correct astigmatism that occurs when a transparent medium is brought into close contact with the incident side of the hologram photosensitive material when photographing an image hologram, and as a projection optical system for the pattern plate at that time. By using a double-sided telecentric optical system, the astigmatism correction effect can be enhanced and the image magnification over the entire hologram surface can be made constant, and an image hologram having no astigmatism, distortion, etc. can be taken. Can do.

  The hologram photographing optical system of the present invention will be described below based on examples.

  FIG. 1 is a cross-sectional view including an optical axis showing the configuration of a hologram photographing optical system of one embodiment. In the present invention, a prism 20 having a polygonal prism shape is used as the prism 20 disposed on the object light 11 incident side of the hologram photosensitive material 10, and the front side surface 23 is perpendicular to the object light 11. It is characterized in that it prevents astigmatism that is caused by obliquely entering the front side surface 23 from being generated.

  In the embodiment of FIG. 1, the photopolymer or silver salt photosensitivity is applied directly or via a refractive index matching liquid to the back side surface 22 of the prism 20 in the shape of a polygonal column having the front side surface 23, the back side surface 22 and the slope 21 as side surfaces. A hologram photosensitive material 10 made of a material or a holographic polymer dispersed liquid crystal element (Patent Document 1) is brought into close contact, and the reference beam 12 is incident on the hologram photosensitive material 10 through a slope 21 of the prism 20 with an incident angle greater than a critical angle. In this embodiment, the object light 11 is vertically incident through the front side surface 23 of the prism 20, and the object light 11 and the reference light 12 incident on the hologram photosensitive material 10 are interfered with each other to record a transmission hologram. It is.

  In this embodiment, the pattern plate 5 arranged in the optical path of the object light 11 is recorded as an image hologram. The hologram photosensitive material 10 is generally tilted with respect to the optical path of the object light 11 (hologram photosensitive). The normal of the material 10 is arranged at an angle with respect to the optical axis of the object light optical path), and accordingly, the pattern plate 5 projected onto the surface is also in the opposite direction with respect to the optical path of the object light 11 corresponding to the tilt. The tilt is arranged. Then, in order to make the imaging magnification of the pattern plate 5 uniform on the projection surface, and to make each principal ray vertically incident on the front side surface 23 of the prism 20, it is between the prism 20 and the pattern plate 5. As the projection optical system 70 arranged at the same position, a double-sided telecentric optical system in which two groups of positive lenses 71 and 72 are arranged concentrically and coaxially and a diaphragm 73 is arranged on the common focal plane is used. .

  Further, in this embodiment, the laser beam generated by the laser 1 is divided into two by the half mirror 2, and the laser beam reflected by the half mirror 2 is converted to a predetermined beam diameter by the beam expander 4 through the mirror 3. As shown, the pattern plate 5 to be recorded as an image hologram is illuminated. The light that has passed through the pattern plate 5 enters the projection optical system 70 as described above, and the object light 11 that has exited the projection optical system 70 enters the front side surface 23 of the prism 20 perpendicularly and is incident on the hologram photosensitive material 10 at a predetermined angle. Incident at. On the other hand, the laser beam that has passed through the half mirror 2 is made to have a predetermined beam diameter by the beam expander 9 through the mirror 8, enters the inclined surface 21 of the prism 20 as reference light 12, and enters the hologram photosensitive material 10 at a predetermined angle greater than a critical angle. Incident at an incident angle.

  Thus, in the hologram photographing optical system of the present invention, the transparent medium 20 is disposed at least in the optical path of the object light, and the hologram photosensitive material is provided on the surface 22 opposite to the object light incident surface 23 of the transparent medium 20. The object light 11 from the pattern plate 5 disposed in the optical path of the object light 11 is incident on the surface 23 on the object light incident side of the transparent medium 20 substantially perpendicularly to photograph an image hologram. Thus, it is possible to correct astigmatism that occurs when a transparent medium is brought into close contact with the incident side of the hologram photosensitive material when an image hologram is photographed. Further, the projection optical system 70 of the pattern plate 5 at that time can be corrected on both sides. By using a telecentric optical system, the astigmatism correction effect can be enhanced and the image magnification over the entire hologram surface can be made constant.

  FIG. 2 is a view similar to FIG. 1 showing a modification of the embodiment of FIG. 1. In this modification, the other prism 30 is arranged on the projection optical system 70 side of the pattern plate 5 in FIG. Different from the embodiment. The other prism 30 is a prism having a polygonal column shape similar to that of the prism 20, and the pattern plate 5 is brought into close contact with the side surface 31 on the incident side, and each principal ray of the object light 11 is perpendicular to the side surface 32 on the emission side. It comes out. By disposing such another prism 30 on the exit side of the pattern plate 5, in particular, the optical path from the pattern plate 5 and the optical path incident on the hologram photosensitive material 10 become substantially symmetrical with respect to the projection optical system 70, Since the occurrence of distortion and curvature of field can be reduced, the arrangement of FIG. 2 is more preferable. In the case of the example of FIG. 2, compensation is made so that the laser light from the beam expander 4 is refracted by the incident side surface 31 of the other prism 30 or the pattern plate 5 on the laser light incident side of the pattern plate 5. However, the optical path compensation prism 40 may be omitted.

  In the above, the optical system in the case where the prism 20 is disposed in close contact with the hologram photosensitive material 10 in the optical path of the object beam 11 when the image hologram is recorded as a transmission hologram has been described. At the time of recording, a prism 20 is similarly placed in close contact with the hologram photosensitive material 10 in the optical path of the object beam 11 so that the reference light 12 is incident on the hologram photosensitive material 10 from the opposite side of the prism 20. .

  The hologram imaging optical system of the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.

It is a figure which shows the structure of the hologram imaging optical system of one Example of this invention. It is a figure similar to FIG. 1 which shows the modification of the Example of FIG. It is a figure which shows the optical arrangement | positioning of the conventional hologram imaging optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser 2 ... Half mirror 3 ... Mirror 4 ... Beam expander 5 ... Pattern plate 6 ... Parallel plate 7 ... Projection optical system 8 ... Mirror 9 ... Beam expander 10 ... Hologram photosensitive material 11 ... Object beam 12 ... Reference beam 20 ... Prism (transparent medium)
21 ... Prism slope 22 ... Prism back side surface 23 ... Prism front side surface 30 ... Another prism 31 ... Another prism incident side surface 32 ... Another prism exit side surface 40 ... Optical path compensation prism 70 ... Projection Optical system 71, 72 ... Positive lens

Claims (4)

Holographic imaging optics for photographing an image hologram by placing a transparent medium in close contact with the hologram photosensitive material in the optical path of the object light and causing the object light from the pattern plate arranged in the optical path of the object light to enter the transparent medium In the system,
Projection optics for projecting the pattern plate onto the hologram photosensitive material through the transparent medium while arranging the object light from the pattern plate to be substantially perpendicular to the surface on the object light incident side of the transparent medium Using a bilateral telecentric optical system as the system,
Another transparent medium is arranged on the emission side of the pattern plate, and is arranged so that the object light from the pattern plate is emitted substantially perpendicularly from the surface of the other transparent medium on the object light emission side. sulfo be a program photographing optical system. Wherein placing a positive lens of the second group as a both-side telecentric optical system coaxially confocal holographic imaging optical system according to claim 1, characterized by using an optical system formed by arranged aperture in a common focal plane thereof . Claim 1 or 2 holographic imaging optical system according the reference light from another aspect is characterized in that it is adapted to be incident of the transparent medium. 3. The hologram photographing optical system according to claim 1, wherein reference light is incident from a side opposite to the transparent medium side of the hologram photosensitive material.

Images